The present invention generally relates to tape guide drum apparatuses, and more particularly to a tape guide drum apparatus having magnetic heads mounted at different height positions so as to record and/or reproduce different kinds of signals on and/or from a magnetic tape in recording regions which are separated in a width direction of the magnetic tape.
A magnetic recording and reproducing apparatus was previously proposed in a U.S. patent6 application Ser. No. 833,861 filed Feb. 26, 1986 entitled "HELICAL SCAN TYPE MAGNETIC RECORDING AND REPRODUCING APPARATUS" in which the assignee is the same as the assignee of the present application. According to the previously proposed apparatus, three kinds of signals constituting a color video signal are recorded on a plurality of tracks which are mutually separated in a width direction of a magnetic tape by use of a plurality of rotary magnetic heads which simultaneously and independently form the plurality of tracks, and a picture having a satisfactory quality and having only an extremely small time base deviation is obtained at the time of a reproduction.
More specifically, a frequency modulated luminance signal is recorded in a lower half recording region of the magnetic tape having a width of 1/2 inch, and a frequency division multiplexed signal of frequency modulated color difference signals and frequency modulated audio signals is recorded in an upper half recording region of the magnetic tape. The frequency modulated luminance signal and the frequency division multiplexed signal are simultaneously recorded on tracks which are formed obliquely to the longitudinal direction of the magnetic tape within the respective recording regions. In order to carry out the recording on the magnetic tape having such a track pattern, it is necessary to use a tape guide drum apparatus having two pairs of heads. A first pair of heads consists of two heads mounted on a rotary drum at mutually opposing positions on a rotational plane of the rotary drum. A second pair of heads consists of two heads mounted on the rotary drum at mutually opposing positions on the rotational plane of the rotary drum. The positions of the first pair of heads substantially coincide with the positions of the second pair of heads on the rotational plane of the rotary drum. On the other hand, the height positions of the heads constituting the first pair are the same and the height positions of the heads constituting the second pair are the same, but the height position of the first pair of heads and the height position of the second pair of heads are different.
Because the tape guide drum apparatus must have the two pairs of heads arranged at different height positions on the rotary drum, the tape guide drum apparatus must have such a special design that the positions of the heads can be adjusted with ease.
For example, it is possible to conceive a tape guide drum apparatus wherein the heads for recording the frequency modulated luminance signal and the heads for recording the frequency division multiplexed signal are fixed on independent mounting plates (bases) and the mounting plates are mounted on the rotary drum with the heights thereof made different from each other. However, according to such a tape guide drum apparatus, it is necessary to adjustment the position of each of the heads after the mounting of the heads is completed. The positional adjustments include adjustments of the height positions of the heads, relative positions of the upper and lower heads, projecting quantities of the heads from the outer peripheral surface of the rotary drum, and relative positions of the heads mounted at mutually opposite positions. As a result, it will be extremely difficult to adjust the mounting positions of the heads with a high accuracy. Furthermore, it will be troublesome to perform such positional adjustments, and this conceivable tape guide drum apparatus is unsuited for mass production.